A fire at a Shell refinery east of Edmonton is partly to blame for a shortage of diesel fuel in Alberta.

Flying J Inc., which operates more than 20 diesel outlets in Alberta, said six outlets have run out of diesel and several others list their supply as "critically low."

Flying J partners with Shell Canada, which had a sour gas leak spark a fire at its Scotford upgrader in Fort Saskatchewan 10 days ago.

Shell spokeswoman Denita Davis said the fire and the increasing demand for diesel at this time of year are contributing to the shortage.

"The Scotford refinery is operating at reduced rates," she said. "It really is as a result of increased demand, tight industry supply and an unexpected supply disruption."

Davis said Shell is importing diesel from the U.S. while it tries to boost production at the refinery as quickly as safety permits.

"Normally we get about 14 loads that go out in a day and right now we're getting three," Cindy Dunbar, a manager at a Flying J facility in Calgary, said Wednesday.

There's no indication when the shortage, which does not affect regular gas supplies, will be resolved.